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Proposed Wording for Mask and Clip Effects on Pointer Events (ACTION-2372)

From: Doug Schepers <schepers@w3.org>
Date: Fri, 05 Dec 2008 18:58:57 -0500
Message-ID: <4939C041.8070704@w3.org>
To: public-svg-wg@w3.org


Per ACTION-2372, here is my proposed wording for the effects of masking
and clipping on pointer-events.  This actually supersedes similar
wording from an earlier erratum, which I have commented out to avoid

Note that we had previously come to slightly different conclusions about
pointer events for clip paths [1], but this new wording is more
desirable and more consistent. [2]


<h3 id="clip_mask_pointer-events">16.6.1 Clipping paths, masking, and
pointer events</h3>

<p>The effects of masking and clipping differ with respect to <a
href="interact.html#PointerEventsProperty">pointer-events</a>.  A clip
path is a geometric boundary, and a given point is clearly either inside
or outside that boundary; thus, pointer events must affect the visible
areas of a clipped element normally, and may effect the clipped areas
depending upon different values of the <a
href="interact.html#PointerEventsProperty">pointer-events</a> property,
as described in the definition of <a href="
paths</a>.  By contrast, a mask (like a filter) is not a binary
transition, but a pixel operation, and different behavior for fully
transparent and 'almost but not fully transparent' would be confusing;
as a consequence, for elements with a mask applied, pointer-events must
still be captured even in areas where the mask goes to zero opacity.  If
an author wishes to achieve an effect where the transparent parts of a
mask allow pointer-events to pass to an element below, a combination of
masking and clipping may be used.</p>


-Doug Schepers
W3C Team Contact, SVG and WebApps WGs
Received on Friday, 5 December 2008 23:59:09 UTC

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